728 years. That's how long Emperor Indom was trapped in a room.
Where was this room?
Nowhere.
If you glanced through the transparent walls, ceiling, or floor, all you'd see was nothingness. It was as if light reflected into your retina, but your brain refused to process it. It wasn't black, but it wasn't anything either.
Indom never dared to stare at it for too long. If he did, his mind would start pondering about the qualities of whatever was out there, and after a while his head would start pounding.
There was nothing in the cube except himself and air. Not even fresh mana would enter, which was a problem for the ruler of dragons.
Indom was one of the Emperors. The first being born in a race, and it's complete overlord.
They were immortal as long as they had mana and their mana core existed. They'd heal from any injury and bounce back from all sicknesses and didn't need water, food, or air to survive.
All they needed was mana.
Something that was not present in his prison.
Even so, he should have survived. He was an emperor, after all, having lived for seventy-eight thousand years.
He was also a dragon, predisposed to have the largest core of any species. His core was repeatedly enlarged during his long lifespan, too.
His mana capacity was an inconceivable 62 teramana. At least, it was at the moment of his sealing.
A mana core is an organ like any other, with one special feature: as long as it had enough mana inside, it was nigh indestructible from the outside.
The mana density of a core is so high it could reflect any magic attack aimed at it. The organ's shell used advanced barriers to protect itself, making breaking it by nonmagical means unlikely.
Even so, it could still be torn apart from the inside.
Usually a core would take in mana, purify it, and store that purified product inside itself for later use by its owner. The rest would be absorbed within it, being used as fuel for the organ. This system worked because mana was so abundant, there was almost no risk of being stranded in a place where it couldn't absorb anything.
This cell was an exception.
Over his imprisonment, his core slowly started the process of atrophy due to insufficient fuel.
There was only one reason he wasn't dead in 100 years, that reason being that Indom's immortality had been considerably sedating the speed of tissue degradation.
By now, his core was damaged, so thoroughly, its capacity was reduced from 62 teramana to a pitiful 3.7 teramana.
His death was inevitable and fast approaching.
Indom sat in his cell, smiling wildly. His hair was tied into a ponytail by a small hairband made of ice, conjured by magic. He was idly playing with a small black piercing on his left ear. If anyone saw him, they'd think he just won the lottery.
"Oh, it's about that time again."
Indom lived for many thousands of years, so his perception of time was much different from that of an average person. When he wanted, he could perceive the world like a normal being, but if he considered it necessary, a hundred years would feel like a month.
Suddenly, blades of wind formed within his open palm, slashing at his own face. They bombarded his spotless, delicate-looking skin.
It wasn't some complex method of hurting himself; he was simply shaving.
Then, from the same palm exited a stream of warm water. This was a combination of water and fire magic.
He felt his newly smooth face, sighing happily.
"Ah, that hits the spot."
How was Indom still sane after having no stimuli for effectively 7 months? Simple. He created a singular source of stimulus. His imagination.
In his mind, he was creating a vivid picture of all the painful and abhorrent ways he'll torture and murder his jailer.
He didn't care about the imprisoning. He considered that a petty squabble between siblings. Sure, his mana core was irreparably damaged, but Indom had wounded his brother's core too. The cause of his hatred was something completely different.
'I will torture you for a hundred years per dead dragon, Utbrus. I will destroy your body over and over and over again until your brain is mush from the pain! I'll keep you as a mindless pet! The instant you bore me, I'll find a way to turn you lucid before I kill you, permanently. In your final moments, you'll have no choice but to comprehend it was mewho did it.'
He clenched his fist, veins becoming more pronounced on his forearm.
'I'll take Enga, Dece, Art, and Crown with me to your shallow grave. We will spit on it and laugh at your pathetic demise. That's my promise to you.'
He tried to imagine the scene for amusement but was distracted by a quiet cracking noise. Normally, it wouldn't be something to react to; however, he hadn't heard a sound that was not produced by him in over 700 years.
He jumped into the cell's corner at the sound like a frightened mana beast. Then, he saw a small crack in the floor of the prison. A tiny stream of light was slowly entering through it, extending towards his core.
Indom didn't detect any malice directed at him, so he let it connect to his decrepit organ. It absorbed a pitifully small amount of mana.
Indom was grinning madly like a gambler who hit it big.